Generally, ceramic wiring substrates are produced by dividing a multi-piece ceramic wiring substrate array into individual wiring substrates along dividing grooves provided on a front surface or a back surface of the wiring substrate array. In connection therewith, there has been proposed a method for producing a multi-piece wiring substrate array, in which a blade having a specific edge angle is pressed against a surface of a green sheet laminate at positions where dividing grooves are to be formed, so that breakage, burrs, etc. are less likely to occur at a metal layer located in a vicinity of the thus-formed dividing grooves during formation of individual wiring substrates from the substrate array (see, for example, Patent Document 1).
In the case where dividing grooves are formed by means of a blade in a multi-piece wiring substrate array through the multi-piece wiring substrate array production method described in Patent Document 1, when the multi-piece wiring substrate array is divided into individual wiring substrates, each side surface of each wiring substrate has a relatively smooth groove surface (i.e., a surface corresponding to each dividing groove formed by the blade) at a portion in the vicinity of a front surface or a back surface of the wiring substrate, as well as a ceramic fracture surface located at a middle portion of the side surface in a thickness direction. Therefore, when a chucking apparatus is employed for conveying each wiring substrate by means of a pair of opposing claws of the apparatus, since each claw tends to slip on a smooth groove surface of the corresponding side surface of the wiring substrate when the claw comes into contact with the groove surface, chucking of the wiring substrate may fail to be achieved. Alternatively, a special chucking apparatus having long claws is required for chucking of each wiring substrate at its fracture surface.
Meanwhile, when individual wiring substrates are to be positioned in each of a plurality of dents of a product tray by means of a positioning jig after insertion of the wiring substrates in the dent, since the positioning jig may slip on a smooth groove surface of each side surface of a wiring substrate due to slight vibration, positioning of the wiring substrates in the dent may fail to be achieved. In the worst case, there may arise a problem in that some wiring substrates jump out of the dent.